The present disclosure relates to a fixing device configured to fix a toner image onto a recording medium and an image forming apparatus including the fixing device.
Conventionally, an electrographic image forming apparatus, such as a copying machine or a printer, includes a fixing device configured to fix a toner image onto a recording medium, such as a sheet.
For example, there is a fixing device including a fixing belt, a pressuring member configured to come into pressure contact with the fixing belt so as to form a fixing nip, a heat source configured to heat the fixing belt, a heating stop device configured to face an outer circumferential face of the fixing belt. In such a fixing device, upon an excessive rise in temperature of the fixing belt, the heating stop device operates so as to stop the fixing belt from heating by the heat source.
In the fixing device configured as described above, there is a concern that, when a facing interval between the fixing belt and the heating stop device is too narrow, the heating stop device operates even though the temperature of the fixing belt does not excessively rise. On the other hand, there is a concern that, when the heat source causes a runaway (when the heat source heats the fixing belt in a state where the rotation of the fixing belt is stopped), a timing at which the heating stop device operates delays.